a) Field of the Invention
The invention is directed to an arrangement for cutting off radiation in projectors and/or illumination devices, particularly when projecting image contents on plane and curved projection surfaces.
b) Description of the Related Art
Laser projectors which can be set up at different locations, especially those using variable focus objective lenses for projecting image contents, and illumination devices require a suitable safety device which ensures, independent from any measurement, control or regulating technology, that the standing area for persons which is defined as the safety zone can not be reached under any circumstances by laser radiation or other intensive light radiation. Such a device is particularly necessary when the projector cannot be installed from the start at a corresponding height above the surface accessible to persons. The lasers to be used with an average power over all emitted wavelengths of xe2x89xa73 W belong to laser class 4. Although the intensity of the laser radiation decreases with increasing distance, the permissible limit values of the maximum permissible irradiation according to EN60825-1:1997 and DIN 56912:1982 at a distance of 10 m are clearly exceeded. ANSI standard Z136.1-1993 and FDA regulation 21 CFR1040 are determining for use in the U.S.A.
According to these standards currently in force, a safe distance above the floor of 3 m (U.S.A.) and 2.5 m (Europe) must be maintained in supervised projectors. Often, this cannot be realized for technical reasons, among others, and is also often not sensible. The arrangement described hereinafter can be applied for projection of image contents on spherical surfaces of all types such as the inner surfaces of domes as well as in any other arrangements for illumination and for projection on plane, cylindrical or otherwise curved surfaces.
Therefore, it is the primary object of the invention to provide an arrangement for cutting off radiation in projectors and/or illumination devices which ensures, independent from any measurement, control or regulating technology, that the standing area for persons which is defined as the safety zone can not be reached or struck under any circumstances by the radiation being used.
According to the invention, this object is met by an arrangement for cutting off intensive radiation in projectors and/or illumination devices whose projection head, which projects the light, is mounted in a receptacle or holder rotatable about an azimuth axis so as to be swivelable about an additional axis arranged vertical to the azimuth axis. It comprises a cutoff mechanism which comprises a coupling member and light-absorbing means or cutoff means, which is fixedly connected with the receptacle and which is rotatable jointly with the latter and with the projection head about the azimuth axis, wherein the light-absorbing or cutoff means are positioned in the cutoff position in front of the light outlet opening of the projection head or of an objective or in an intermediate image plane located within the projection head. The arrangement is suitable for application particularly with projection of image contents on plane, arched, or curved projection surfaces in the first patent claim. Modifications and details of the invention are indicated in the further claims.
Accordingly, it is advantageous when the entire cutoff mechanism is swivelable about the additional axis extending perpendicularly to the azimuth axis.
In order to control the movement of the entire cutoff mechanism about the additional axis relative to the projection head depending on its movement or angular position, loaded transmission members are provided between the cutoff mechanism and the projection head. Accordingly, it is possible to provide a disk cam or other transmission gear unit by means of which various fast angular movements of the cutoff mechanism and projection head are realized. It must only be ensured that the light-absorbing and light-stopping means of the cutoff mechanism completely interrupt the light when the projection head has reached an angular position in which the light exiting from it can radiate into the above mentioned safety zone for persons.
In order to be able to adjust the light-stopping or light-absorbing means of the cutoff mechanism in an optimum manner, the latter can be adjusted in the direction of the optical axis of the projection head and/or in a plane perpendicular to this optical axis.
The light-absorbing means of the cutoff mechanism are advantageously constructed as a light trap which has a honeycomb structure or formed of light-absorbing material.
It is also possible to provide the light-absorbing means of the cutoff mechanism with a light-absorbing surface coating and/or surface structure.
Since heat is generated in most cases when eliminating light by cutting off or light absorption, it is advantageous when the light-absorbing means of the cutoff mechanism have means for dissipating or regulating heat. For example, cooling ribs, known per se, or other surface-enlarging elements can be provided at the light-absorbing means. It is also possible to cool the heated structural component parts by means of a flow of coolant; however, this requires a greater expenditure on apparatus.
The described arrangement realizes a cutoff mechanism which is fixedly connected with the movement of the projection head or of an objective about an azimuth axis and which serves as a light trap. This cutoff mechanism is guided along with every movement of the projection head or objective above the plane of projection by means of a rigid coupling with the projection head and is accordingly always located in the direction of projection (azimuthal movement). The second movement axis, said additional axis, of the projection head or projector about which a vertical swiveling is realized can be controlled in any manner. The cutoff mechanism begins to operate without any additional controlling when the projection head could project into the safety zone, irrespective of the radiation angle adjusted at a variable focus lens or at another optical projection system. While the projection area can vary somewhat, the system can be adjusted in every case in such a way that projection or irradiation never occurs in the safety zone even in an unfavorable position of the projection head.
Scatter light which may occur must be below the dangerous limiting values.
The system can be adjusted for different geometric conditions, but is fixed with respect to application. The cutoff means can be constructed as a plane, curved or arched plate.
Compulsory adjustment of the penetration or immersion position of the objective of the projection head can also be realized, for example, when using an elevator system for the entire projection head or illumination device that is used. For this purpose, the change in setup geometry, e.g., by elevating the setup location above a standard position, is used in order to automatically expand the projection area of the projector, but without projecting in the intended safety zone. By means of fixed mechanical coupling of the vertical adjusting means of the projection head to the adjusting means of the cutoff mechanism, the latter adjustment remains effective irrespective of any control in any position of the arrangement in the azimuth plane.
The arrangement according to the invention is fully functional for horizontal as well as inclined setup of the projection head or illumination device. The inclination of the azimuth axis also characterizes the inclination of the projection head and, therefore, also the inclination of the cutoff mechanism and, therefore, also the inclination of the safety zone. Accordingly, the arrangement according to the invention is also suitable for application, for example, for projecting image contents in inclined domes.
The invention will be described more fully in the following with reference to an embodiment example shown in the accompanying drawings.